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Replacing Old Furnace/hot Water

Hello!

My oil fired boiler and burner is 47 years old and it's time to replace them with another oil fired system (I don't have gas line). Before replacing, I'm updating the insulation and air sealing the house as per recommendations from an energy audit. I've done some investigation myself, have asked my friends and talked to couple of oil companies. I've the following questions that still remain unanswered -

1) Outside combustion air to oil burner: I need to install one, since my boiler room will be rather small, after I finish my basement. As I understand, this brings the outside air to the burner directly.

My first question - is it a sealed system, i.e. the cold air goes directly from outside to the burner via a pipe? Or the cold air will come to the boiler room, in which case the boiler room will be really cold in the winter and some of that cold air can leak upstairs too.

Second question - Does this system work with any burner, more specifically, Reillo and Carlin?

2) I want an outdoor reset, does it work with any boiler, more specifically Weil McClain or Buderus?

3) I'll have three zones, one for each floor. Which of the following two is a better option -

(a) Three separate circulator pumps
OR
(b) One circulator pump with three separate zone valves.

In case (a), I'll have hot water at least in two zones, in case a circulator pump is down. However, how frequently do they go down. I've been living in this house for last 12 years and nothing happened to them.

4) I've the following two boilers in mind: Weil McClain WGO-4 (i.e. the one that works with an indirect water heater) and Buderus. Which one is better?

5) I've the following two burner in mind: Reillo or Carlin? Which one is a better option?

if your going for the most out of a boiler the Buderus is the way to go, Weil Mclain does make a 3 pass boiler but only with the NX burner, which i would stay away from, there are other 3 passes out there all at 86%, the Reillo is the way to go and you can get the burner set up for out side air, ifc circulators and you'll have good recovery on your indirect, out side reset works well with any boiler and indirect

Without a doubt, go with the Buderus. This boiler gives you the best bang for your buck. I always prefer circs over zone valves. The Riello is a very solid performing burner. I would worry more about the guy setting it up properly. Any system will perform well if properly sized/installed. Good luck.

i personally love the biasi b/10. a great, well built tripple pass, that has little water mass. it is cheaper than the wm. and has a lifetime warranty. silicone impregnated cast iron block and can be converted to gas by just a burner swap.

I alos like the Biasi but choose the

Buderus over a WM. They have their own OD reset control you could get.
Go Riello. I have a BF-5 on my boiler and love it. (Balanced Flue model with the air intake housing) Get 2 cirs, one for the zones with zone valves and one for the indirect tank. Wasting energy on 4 oversized pumps when 2 can do the job doesn't make sense to me. Also take a look at Burnham's MPO. 3 pass and USof A made!
Easy to clean. Slap on a Tekmar OD reset control and you're good to go!

Something else to think about ....... what kind of chimney does your existing boiler vent into? A new boiler will be a lot more efficient than the old one and then if you add a reset control you can potentially cause condensation issues in some types of chimneys.
Water running down your chimney all over the floor in a finished area will totally ruin your day.

Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

Never thought of condensation in my chimney and none of the 3 contractors mentioned this as a potential problem. Thanks for bringing this out. My system WILL use a chimney (approx 30 ft high) for exhaust. Is there any way to prevent condensation? Not only the water will come to the floor, additionally it can damage the chimney liner.

My chimney is a regular 40 years old chimney, the same age as my house.